This study focuses on the pathologic and normal development of chick embryo digital tendons along with investigation of the repair of these same structures. The purpose of the work is to determine factors that lead to a regenerative response following injury of tendons and also those that interfere with regeneration. The significance of the project is to determine ways of manipulating the above factors to provide for optimal results in human digital tendon injuries. The specific projects under way in the laboratory at the present time involve the study by means of electron microscopy of the development of chick embryo tendons following paralysis by means of constant infusion of curare. In addition, the growth of chick tendons is being investigated in relation to increase in cell number versus increase in extracellular material. The biochemical determination of DNA concentration and hydroxyproline concentrations are used to provide this information. The laboratory is also studying the fine structure of human surgical specimens of Dupuytren's contracture. A study is underway to determine the effects of immobilization vs. early motion on the repair of severed chick tendons. With this study a collagenase assay system is being set up to determine if collagen removal, post injury, is affected by motion or suturing.